Assessment of mechanical properties and fatigue performance of a selective laser melted nickel-base superalloy Inconel 718

Pei, Changhao; Shi, Daxin; Yuan, Huang; Li, Huaixue

doi:10.1016/j.msea.2019.05.007

Cited by 128 publications

(36 citation statements)

References 38 publications

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“…The higher scatter in the parallel and diagonal orientations is due to the presence of numerous LoF defects that act as crack initiation sites ( Figure 15 a–c). Similar defect-induced scatter in strain-controlled fatigue testing of LB-PBF Alloy 718 have been reported [ 14 , 15 ]. In the parallel specimens, LoF defects were oriented normal to the loading direction and in the diagonal specimens, LoF defects were oriented at 45° to the loading direction.…”

Section: Resultssupporting

confidence: 78%

“…Apart from using rotating bending and bending fatigue tests, which are discouraged by the Metallic Materials Properties Database Development and Standardization (MMPDS) for the purpose of design and analysis of structures in aerospace systems [ 5 ], fatigue studies on LB-PBF Alloy 718 have been focused on high cycle fatigue (HCF) performance evaluating the influence of defects [ 6 , 7 ], geometrical notches [ 7 , 8 ], surface roughness characteristics due to part orientation [ 7 , 9 , 10 , 11 , 12 ], and texture [ 13 ]. Furthermore, only a few investigations on low cycle fatigue (LCF) behaviour of LB-PBF Alloy 718 exist [ 14 , 15 , 16 , 17 , 18 ]. In these studies, neither the anisotropy in fatigue behaviour has been characterized thoroughly nor a method to handle this anisotropy has been proposed.…”

Section: Introductionmentioning

confidence: 99%

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On the Microstructure of Laser Beam Powder Bed Fusion Alloy 718 and Its Influence on the Low Cycle Fatigue Behaviour

et al. 2020

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Additive manufacturing of Alloy 718 has become a popular subject of research in recent years. Understanding the process-microstructure-property relationship of additively manufactured Alloy 718 is crucial for maturing the technology to manufacture critical components. Fatigue behaviour is a key mechanical property that is required in applications such as gas turbines. Therefore, in the present work, low cycle fatigue behaviour of Alloy 718 manufactured by laser beam powder bed fusion process has been investigated. The material was tested in as-built condition as well as after two different thermal post-treatments. Three orientations with respect to the building direction were tested to evaluate the anisotropy. Testing was performed at room temperature under controlled amplitudes of strain. It was found that defects, inclusions, strengthening precipitates, and Young’s modulus influence the fatigue behaviour under strain-controlled conditions. The strengthening precipitates affected the deformation mechanism as well as the cycle-dependent hardening/softening behaviour. The defects and the inclusions had a detrimental effect on fatigue life. The presence of Laves phase in LB-PBF Alloy 718 did not have a detrimental effect on fatigue life. Young’s modulus was anisotropic and it contributed to the anisotropy in strain-life relationship. Pseudo-elastic stress vs. fatigue life approach could be used to handle the modulus-induced anisotropy in the strain-life relationship.

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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

On the Microstructure of Laser Beam Powder Bed Fusion Alloy 718 and Its Influence on the Low Cycle Fatigue Behaviour

et al. 2020

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“…Johnson et al found that the fatigue property of the AM specimen was lower than that of the forged specimen due to the presence of the carbide, oxide inclusion and porosity defects near the surface [ 9 ]. Pei et al also reported that SLM IN718 had inferior fatigue properties than the forged counterpart, and the difference was more obvious with the increase in cycles, indicating more sensitivity to defects for SLM alloy in the very-high-cycle fatigue (VHCF) regime [ 10 ]. However, Gribbin found that the role of porosity present in the direct metal laser sintered IN718 specimens is not as significant at low strain amplitudes as it is at high strain amplitudes [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Very-High-Cycle Fatigue Behavior of Inconel 718 Alloy Fabricated by Selective Laser Melting at Elevated Temperature

et al. 2021

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This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 108 cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 108 cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 107–108 cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 107–108 cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.

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“…The anisotropic behavior of additive manufactured metals has been investigated in many studies [27][28][29][30] in order to reduce it by various post-processing techniques, like heat treatment optimization or hot isostatic pressing (HIP). The studies conducted on additively manufactured IN 718 Ni-based superalloy showed that its anisotropic behavior depends on the building angle, building orientation, scanning strategy, phase development, texture, and grain morphology [30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Microstructural and Tensile Properties Anisotropy of Selective Laser Melting Manufactured IN 625

et al. 2020

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The present study was focused on the assessment of microstructural anisotropy of IN 625 manufactured by selective laser melting (SLM) and its influence on the material’s room temperature tensile properties. Microstructural anisotropy was assessed based on computational and experimental investigations. Tensile specimens were manufactured using four building orientations (along Z, X, Y-axis, and tilted at 45° in the XZ plane) and three different scanning strategies (90°, 67°, and 45°). The simulation of microstructure development in specimens built along the Z-axis, applying all three scanning strategies, showed that the as-built microstructure is strongly textured and is influenced by the scanning strategy. The 45° scanning strategy induced the highest microstructural texture from all scanning strategies used. The monotonic tensile test results highlighted that the material exhibits significant anisotropic properties, depending on both the specimen orientation and the scanning strategy. Regardless of the scanning strategy used, the lowest mechanical performances of IN 625, in terms of strength values, were recorded for specimens built in the vertical position, as compared with all the other orientations.

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Assessment of mechanical properties and fatigue performance of a selective laser melted nickel-base superalloy Inconel 718

Cited by 128 publications

References 38 publications

On the Microstructure of Laser Beam Powder Bed Fusion Alloy 718 and Its Influence on the Low Cycle Fatigue Behaviour

On the Microstructure of Laser Beam Powder Bed Fusion Alloy 718 and Its Influence on the Low Cycle Fatigue Behaviour

Very-High-Cycle Fatigue Behavior of Inconel 718 Alloy Fabricated by Selective Laser Melting at Elevated Temperature

Microstructural and Tensile Properties Anisotropy of Selective Laser Melting Manufactured IN 625

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